2007.12.10 01:01 "Re: [Tiff] dpi settings", by Graeme Gill
Here in the US, the ruler that I have available is marked with inches and centimeters. Are you saying that rulers in the rest of the world are no longer marked with centimeters? If they are not marked with centimeters, then what are they marked with? A ruler marked with millimeters or meters would not be so convenient.
I'm saying that for some time, cm is a deprecated unit, and mm is the preferred unit. Yes, many rulers sold here are marked only in mm (although, naturally the markings are at 10mm intervals :-) In some senses this is a subtle distinction, but it's still an irritation to be converting to/from cm, and adds possibly confusion and room for misunderstanding.
It seems natural that centimeters was used since it is easiest to measure the width and height of a computer screen or page-sized object (e.g. sheet of paper) in centimeters rather than in meters or millimeters.
I know what you mean and had a similar reaction myself initially, but it turns out in practice that mm is pretty convenient, especially for paper size, which is where I trip over the cm/mm thing all the time with desktop applications. It's a whole number with adequate precision for very many everyday tasks (woodworking is another one that springs to my mind). For grosser scales, a one digit decimal on the meter is often the way to go (ie. 3.1 meters). It's true though that in advertisements, cm is used for TV display sizes. I guess for screen rulings and pixel density pixels/mm isn't so great, although it is something I've standardized on internal in my software (reduces my confusion).
In much official usage (ie. rainfall - when there is any!), mm are what's used. It's hardly uniform amongst the population - when the metric system was introduced here we were taught cm, since they where closer in size to inches, but since then there has been an attempt to standardize on prefixes that are a multiple of 1000, that's been partially successful.
I think that Andrey's observation about technical and non-technical use probably reflects the situation here in Australia as well to a fair degree, and it will come down to what's currently being taught in schools as to what future trends in popular usage are.